The development of horizontal continuous casting systems has permitted the casting of extended length constant cross-section castings, such as steel castings, in an economical and convenient manner. While the structures of horizontal continuous casting systems vary from manufacturer to manufacturer, the operative details are generally similar. These caster systems are described in U.S. Pat. Nos. 4,437,509; 4,520,860; 4,532,977; 4,580,614, and 4,774,996, the disclosures thereof incorporated herein by reference.
In the operation of a continuous caster, a supply of molten metal is provided to a tundish prior to the initiation of the casting process. Thereafter, a starter bar having a cross-section corresponding generally to that of the to-be-formed casting is inserted into the casting mold. Next, a slide gate on the tundish is opened and the molten metal within the tundish flows out through the exit port into the casting mold and welds to the starter bar. The drive motors then initiate the desired casting motion for the casting system and the process begins.
The motion of the casting which is forming within the casting mold comprises a series of motions in accordance with a predetermined motion profile. The motion profile most commonly used includes a series of short forward motions referred to as casting strokes. In a preferred system each forward motion is followed by a short reverse motion. Thus, in the preferred motion profile for a horizontal continuous casting operation, a series of motion cycles occur, each of which includes a forward casting stroke followed by a brief reverse movement.
Once the casting system has begun its steady state operation, the various parameters of the casting process must be carefully controlled to provide optimum castings. It is important that these various parameters are rapidly and precisely interrelated and controlled to provide quality castings. In order to obtain precise control of the motion of the casting, it has been proposed to utilize a computerized continuous casting system. Thus, Kosco, U.S. Pat. No. 3,614,978 discloses a computerized continuous casting system control responsive to strand position. In the system of the Kosco patent, the motor driving the casting is always going forward and, additionally, the system is based on positional control. As a result, the system cannot be utilized with a casting system having a series of forward and reverse motions. Further, as a result of the positional control features, the system is relatively slow and complex when the motion control is tied into the operating parameters such as furnace temperature, coolant flow, coolant temperature, and the like of the caster.
Accordingly, there is a need for a motion control system for utilization with horizontal continuous casters which is simplified, rapid, and which permits precise motion control even when tied into the operating parameters of the caster.